This application proposes to conduct a comprehensive study of brain imaging and behavior in 60 school-age children (age 7-11 years) with Down Syndrome (DS), as a supplement to a study of brain imaging and behavior in school age children with idiopathic autism, autism-related conditions (e.g., language delay) and typical development, who have been followed longitudinally since infancy, as part of an Autism Center of Excellence (ACE) Network, referred to as the Infant Brain Imaging Study (or IBIS). The supplemental funding will also support a comparison of brain structure, including white matter pathways and functional networks, in children with DS in contrast to the 3 groups of children from the IBIS network. The proposed study directly addresses component 2 of the DS research objectives. The overarching objective is to create a cohort of school-aged children with DS with deep brain and behavior characterization. The research protocol includes multi-modal neuroimaging including sMRI, DTI, and fcMRI and cognitive and psychiatric assessments. The proposed study will be most likely the largest pediatric neuroimaging study of DS and can serve as a baseline cohort for a longitudinal study of children with DS into adolescence. Consistent with the 2014 NIH research plan on DS and the mission of the INCLUDE initiative, the objective of this proposal is within the research priorities of the Intellectual and Developmental Disabilities Branch and NICHD. Understanding the underlying brain structure and its relationship with behavioral phenotype is a priority needed to advance the field.